6-built-ins-javascript.md

Drawing Hands : Build ins written in javascript - John Dalton

Implementing parts or the whole of a language in the language itself

Overview

• For example - [].indexOf ; which is different between mozilla and v8

• By using a subset of functionality you can get better performance than built-ins

  • You can even add features and still have better performance
  • You can optimize for common cases for your domain better than the general domain

• Intl

  • Good because writing it in js simplifies reading/understandably
  • Bad because of extra js functionality being exposed
  • Bad because of heavier boilerplate
  • Ugly: preventing tainting of js, testing, ensure correct stack behavior

• The good

  • Easy to develop
  • thus more contributions
  • Performance (inlining for free)
  • Experimental API

• The Bad and Ugly

  • No silver bullet for performance
  • "The hidden cost of javascript natives" - a talk in 2012 on a similar topic
  • We may have to write our own versions in order to get better performance than using the built ins

• Chakra - the js engine for IE-Edge

  • attempts to make built-ins more performant
  • optimize paths to ES6